What's up with my Samsung Plasma? :(

[Ray Luxury-Yacht]

Was watching my 6 year old Samsung 42" Plasma, and suddenly the screen went very dark - almost like I'd turned the brightness down to zero.

There's obviously a fault with it - was wondering if anyone knew what it might be, and how to fix it?

Thanks guys. Picture below - you can see how dark it is:

[GingerWizard]

Maybe a light sensor? Randomly auto adjusting to somthing new???